Control mechanism



Nav. 19, 194s. F. v. HART am 2,411,270

CONTROL MECHANISM Filed Feb. 9. 1942 5 Sheets-Sheet l Nov. 19, 1945. F,v. HART Erm.

CONTROL MECHANISM Filed Feb. 9, 1942 5 Sheets-Shut 2 Nov. 19, 1946. F.v. HART ETL CONTROL MECHANISM Filed Feb. 9, 1942 5 Sheets-Sheet 3 www@Nov. 19, 1946.

F. v. HART Er AL CONTROL M'ECHANISM Fiied Feb. 9, 1942 5 sheets-sheet 4Nov. 19, 1946.

F. v. HART ETAL 2,411,270

CONTROL MECHANI SM Filed Feb. 9, 1942 5 Sheets-Sheef 5 R/oHT m LEFTFgtl. I .232

stented Nov. 19, 1946 CQNTROL MCHANISM tion oil New Jersey applicatiesseaman a, ieee, sans?. (ci. sev-iii 9 Claima This invention relates to.control mechanism has for an object the provision of novel and improvedmeans for controlling the power movementV of the gun.

In apparatus for training a machine gun, or other relatively smallcaliber gun, it is usual to mount the gun for swinging movement abouttwo axes at right angles to each other and to provide hand g'rlps on theback end of the gun by means of 'which it may be moved around until itssights are brought to bear on the target and thereafter held in thisposition while it is fired, as, for example, is disclosed in UnitedStates Letters Patent No. 2,051,034, granted on August 18, 1936,'upon anapplication led in the'name of Ralph M. Ferguson. Where the gun isheavy, or subjected to theaction of some exterior force, such, forexample, as that caused bythe slip stream from the propellers of anairplane, the

. physical eilort required for moving the gun, and

also for holding it trained on the target, is considerable and such asmaterially to decrease the speed and accuracy of aiming. This isespecially the case when the gunner is operating at high altitudes,where even the slightest physical e'ort becomes very tiring. It has,therefore, been proposed to employ power-operated means for moving a gunto train 'it and to provide manual controls, operated by the gunner, forcontrolling the operation of the power-operated means. However, in priorapparatus of this type, the control of the power-operated mechanism isremote, indirect and/ or discontinuous, so thatV direct manual movementof the gun is not simulated, or

are so constructed that an awkward technique unfamiliar to the gunnermust be employed in training the gun. Thus, while the use of priorapparatus of this type relieves the gunner of most of the physicaleilort required for moving the gun, it does not give him the samenatural feel which hemwould experience in moving the v gun by hand andwhich is quite essential for highest accuracy and most readymanipulation of the gun. Also, such apparatus usually involves the u'seof complicated, bulky and expensive control mechanisms. t Y

It is, therefore, a more speciiic object of this invention to providenovel and improved mechanism for so controlling the movements lof apower-operated gun that direct manual -movement thereof by means of theusual hand grips is the same technique in training the gun as he lwouldii'he were actually moving the gun manually and by means or" the usualhand grips.' To this end, an important feature of this invention residesinthe provision in power-operated gun-training apparatus of universalcontrol means including a `control handle, located in substantially thesame position as and corresponding to one ofthe usual hand grips, thespeed. direction and extent of movement of which directly andcontinuously determine the speed, direction and movement of the gun.

More particularly and when, as in the herein illustrated embodiment ofthe invention, the power-operated means for moving -the gun are twodouble-acting fluid-pressure motors arranged to swing a gun about twotransverse axes, the novel controlling mechanism may comprise, inaccordance with further features of the invenl tion, two reversingvalves, each having a shifteble valve member, for directly controllingthe'direction and rate of ilow of pressure fluid to vand exhaust fromthe motors; a control handle common to both valves and carried insubstantially the same location on the back end of the gun as aconventional hand grip, the handle being movable at will by the operatoralong any ofja plu rality of paths corresponding to the paths alongwhich the back end of the gun moves as it is swung about either or bothof saidaxes; and op# erating connections directly connecting the controlhandle and the shiftable valve members so that the shiftable valvemembers are directly and continuously under the control of the controlhandle. The reversing valvesA and operating connections, as hereinillustrated, are so constructed and arranged that when the controlhandle is moved by the operator inany direction, at any speed and to anyextent, one or both of the duidpressure motors are immediately operatedto swing the` gun `about one, or both, of said axes, so that its backend will be moved in the same direction, at the same speed and to thesame eX- tent as the handle is moved. That is, the direction in whichthe handle is moved determines the direction in which one or both of theshiftable valve members are moved with respect to neutral positions inwhich they are normally retained by yieldable means, so 'that the pathalong which the back end oi the gun is moved by the fluidpressuremotors, and the direction of its movement alongthis path, are directlyand continu- 'l ously determined bythe movement of the handie; while thespeed of movement of the handle simulated and the operator enabled toemploy determines the amount the shiftable members are displaced. at anyinstant, thus directly and of' the gun. The extent to which the gun ismoved is likewise directly and continuously determined by the extentofmovement yof the handle since, when movement of the handle is stopped,the operating connections return the shiftable valve members to theirneutral positions, thus cutting off the flow of pressure iuid toandexhaust from the motors to stop movement of the gun and effectivelyto block its movement until the handle is again moved by the operator.The power-operated means, e. g., the fluid-motors, are hence directlyand continuously under the control of the movable control handle and theoperator, simply by moving the handle against the very small resistanceof the above-mentioned yieldable means, can cause the gun to be moved bypower in exactly the same manner as if he were actually moving it byhand and by stopping movement of the handle can cause the gun to besecurely held against movement while it is fired.

Other more speciiic features of the invention reside in the provision;in mechanism for controlling the operation of duid-pressure-operatedmeans for moving a gun, of the type of reversing valves here employedfor controlling the flow of pressure fluid to and from fluid-pressuremotors; of novel mechanism for operating the reversing valves from asingle control handle mounted on the back end of the gun; and of meansfor steady. ing the movements of the control handle so that theoperation oi the motors and movements of the gun are smooth and even.

The above and other objects and features of the invention will appear inthe following detailed description of the illustrated embodiment thereofshown in the accompanying drawings, and will be pointed out in theclaims.

.ln the drawings,

Fig. 1 is a view in side elevation of an apparatus embodying thefeatures of this invention;

Fig. 2 is a sectional view at an enlarged scale of the apparatus shownin Fig. l taken onthe line I-II of that figure and locking in thedirection of the arrows;

Fig. 3 is a sectional view of a portion of the apparatus taken on theline Illlli oi Fig. 2 and looking in the direction of the arrows;

Fig. l is a plan view at an enlarged scale of the right-hand end portionof.' the apparatus shown in Fig. l illustrating the controlling valve nmechanism, the control handle, and the operating connections between thecontrol handle and valve mechanism;

Fig. 5 is a view in end elevation of a portion of the apparatus shown inFig. 4 with some parts in section;

Fig. 6 is a sectional view of the control valve mechanism taken on lineVI-VI of Fig. 4 and looking in the direction of the arrows;

Fig. 7 is another sectional view of the control valve mechanisms takenon line Vil-VII of Fig. 6 and looking in the direction of vthe arrows;

Fig. 8 is a view in side elevation of one of the elements of the controlvalve mechanism shown .inFig 6;

Fig. 9 is a schematic layout of the operating and controlling mechanismsof the apparatus shown in Figs. 1 to 8; and

Fig. 10 is a view on an enlarged scale of a portion of the control valvemechanism shown in Fig. 6, with some .parts broken away and others insection.

Referring to the drawings, and particularly Figs. l, 2, 3 and 4 thereof,the invention is herein illustrated as embodied in an apparatus for .aai1,270

training a gun having a breech portion I6 and a. barrel l2. lIwo adaptorbars I4, i4 are mounted one on each side of the gun and each of these rbars extends from the back end of the breech portion forwardly to ajoint adjacent to the barrel. These adaptor bars support the gun forswinging movements about a horizontal axis on trunnion pins i6, i8 (Fig.2) journaled in bearing bushings 26, 22 carried by the upper ends of twosupporting plates 24, 26. A shield of armor pleite 28 is also secured tothe forward ends of the adaptor bars by means of brackets 30, 30. Attheir lower ends these two supporting plates 24 and 26 are joined to ahu-b 32 which is journaled for 4swinging movements on a Kingpin 34, theaxis of which is at right angles to the axis of pins I6 and i8, thatextends through the hub and into a post 36. At its lower end the post isflattened to nt between upstanding portions g8,

4 6 of a carrier block 42 and is held in assembled relation on thisblock by means of a'crossl-'pin t4 and a spring-pressed plunger 46 inthe portion GQ. The upper end of the kingpin is provided with a flange48 while its lower end has an annular locking groove 56 into which aspring-pressed locking pin 52 projects.

The flange 48 holds the hub 32 down on the upper end of the post 36.When the plunger 46 is withdrawn, the post may be swung forwardly (Fig.l), about. the pin 44, into a horizontal position for stowing the gunaway.

The carrier clock 42 is adjustably supported on an arcuate track 54mounted on a member 56 (Fig. 1) and has a clamping mechanism, includinga handle 58,' -by means of which the block may be locked in any desiredposition on the track. The member 56 may be any flxed struc tural memberon which it is desired to mount the gun and, in the illustratedarrangement, is a part of the fuselage adjacent to one end of thegunners cockpit in an airplane. Thus the gun is not only mounted fortraining movements about two transverse axes at right angles to eachother, by moving its back end in one direction or the other along any ofa plurality of paths, but the whole mount may be quickly moved along thearcuate track. 5t into any one of a number of different adjustedpositions to render the gun more effective in use, particularly whenfiring at targets on either side of the cockpit.

Movements of the gun in the above manner about the two transverse axesprovided by the trunnion pins i6, i8 and the kingpin 34 are efi'ected bypower-operated means comprising double-acting fluid-pressure motors 60and 62 (Figs. l and 2) both of which, as illustrated, are under thecontrol of a single movable control handle 6:3 which preferably, and asshown, is mounted directly on the back end of the gun itself (Figs. l, 4and 9). Also mounted on the back end of the gun is a fixed handle 66(Fig. 4) adjacent to which is the iiring. trigger 68 (Fig. 1). Thesehandles are in the same location on the gun as the usual hand gripsheretofore provided for use in training the gun manually. As willpresently be explained, the control handle 64 is so con-` nected to 4theshiftable valve members of two reversing Valves for directly controllingthe operation of the motors 66 and 62 that movements of the controlhandle by the operator will cause lilre movements to be imparted to thebackend of the breech portion Ill of the gun by the mo tors, whileholding the control handle against ni ...rent will cause the shiftablevalve members to be so positioned that .the gun is held fixed by fluidtrapped in the motors. The arrangement is, therefore, such that manualmovement of the gun is exactly simulated with substan-I tially no effortrequired by the operator either in aiming the gun or in holding it xedon a target.

The motor 60, which swings the gun about the trunnion pins I8, I8,comprises a double-ended cylinder which is secured to the adaptor bar |4on one side of the gun (Figs. 1 and 2) and which has ears '|2, 'l2journaled on the pin I8. Secured to the upper end of the supportingplate 26 is a block 14, through which the pin I8 extends,

and this :block is shaped to form a quadrant 'I6 that extends downbetweenthe ears '|2, '|2 and midway between the opposite ends of thecylinder l0. Mounted in the cylinder is a double-ended piston 'I8provided with rack teeth 88 which mesh with pinion teeth 82 cut on thequadrant (see Figs. 1, 2 and 9). Pipes 84 and 86 lead from the oppositeends of thecylinder '|0 to a reversing valve 88 which controls the iiowof pressure fluid to, and its exhaust from, the spaces gr chambers 88and92 back of each end of the piston 18 (Fig.

' 9). Since the block 14 and quadrant 16 are fixed to the supportingplate 26, when a. shiftable valve Vmember of the reversing valve 88 ismoved into position to permit pressure Auid to ow through pipe 84 intothe chamber 88 at the left-hand end of cylinder '|8 (Fig. 1) (upper endin Fig. 9), and to permit fluid to be exhausted from the chamber 92 atthe opposite end of the cylinder through the pipe 86, the cylinder willmove relatively to the piston and will be rocked about the pin |8 in aclockwise direction (Fig. 1), and the back end of the breech portion ofthe gun, to which this cylinder'is secured through the adaptor bar I8,will move downwardly. Conversely, when the shiftable valve member of thereversing valve 88 is moved into position to permit pressure fluid toflow through pipe 86 into the chamber 92 and fluid to exhaust from thechamber 90 through pipe 84, the gun will be swung reversely in acounterclockwise direction about the axis of pin' I8 and the breechportion of the gun accordingly will be moved upwardly. As will be seenfrom an inspection of Fig. 9 and the legends thereon, and as will beexplained more in detail below, movement of the control handle 64, up ordown from a midposition, moves the shiftable member in the directionimmediately to start the motor 60 into operation for moving the back endof the breech portion of the gun in the same direction. .When the handleis in the mid-position, as shown in Figs. 1 and 9, the shiftable valvemember is held in a neutral position in which ow through the pipes 84and 86 isentirely cut off and movement of the about the horizontal axisof pins I6 and I8 is effectively blocked by the iluid trapped at eachend of the piston 18.

'Ihe motor 62, which swings the gun about the axis provided by the'kingpin 34 (Figs. 2 and 3), comprises a double-ended cylinder 94 whichis secured to the lower ends of the supporting plates 24, 26. Mountedwithin this cylinder is a doubleended piston 86 which is provided withrack teeth 88. 'I'hese rack teeth are in mesh with pin- Aof the breechportion of the gun, which is carried by the supporting plates 243, 26,will be swung to the right, as viewed in Fig. 9. Conversely, when theshiftable valve member of the reversing valve |08 is moved into positionto admit pressure uid through hose |86 and to exhaust it through hoseRIM, the breech portion of the gun will be moved in the oppositedirection or to the left. (As is shown =by the legends on Fig. 9 and aswill be exlplained in detail below, movement of the control handle 84 tothe right or left, from a midposition, moves the shiftable valve memberin the direction immediately to start the motor 62 into operation formoving the back end of the breech portion of the gun to the right orleft, respectively. When the handle is in the mid-position, as shown inFig. 9, the shiftable valve member is held in a neutral position inwhich it cuts off the tlow of fluid through the hoses |88, |08 and trapsfluid at each end of the piston 98, thus blocking movement of the gunabout the axis of pin 34. Thus the direction of movement of the back endof the gun by the motors 68 and 82 is directly and continuouslydetermined by the direction of movement of the control handle 88 by theoperator.

The control handle 68 (Figs. 1, 4, 5 and 9) which is common to bothreversing valves, is mounted on the back end of the breech portion ofthe gun for movement relative thereto in opposite directions along anyof a plurality of paths in the following manner. This handle is pivotedat its lower end to one arm of a bell-crank lever H8 andat its upper endto a straight lever I6. Each of these levers is fulcrumed for turningmovement about a horizontal axis on a block ||8 and these blocks areeach pivotally connected to a :bracket |20 for swinging movement aboutan axis at right angles to said horizontal'axis. These blocks are Joinedby a strap |22 from which an arm |28 extends. The bracket |20 is securedat its lower end to one of the adaptor bars I6 and the showing of thehandle at-the lower righthand part of the view, and that of thefluid-pressure motor 60, is in side elevation, while the showing of thehandle at the lower center, and that of the motor 62, is in plan. Thevalves 88 and |08 are shown in schematic cross-section and' right-handend views of these valves, shown associated-with the handle 66, havebeen swung into the plane of a plan view and, as will be apparent fromthis g'ure, the handle 68 can be moved, from a mid-position, in oppositedirections along any of a plurality of paths. These movements of thehandle are transmitted through the links |28 and |38 directlylto the twoclamping rings |82 and |36 which, as will now be explained, operate theshlftable valve members of reversing valves 88 and |08.

F.eierring to Figs. 6 and 9, these 'two valves are made in a singleblock |68 which has two parallel through-and-through bores |62, |66.Liner sleeves |46, |48 within the bores provide operating cylindersrespectively for two valve spindles |56, |62. The spindle |60 has fourspaced piston portions |50a, lilb, |5|lc and |56d, and the spindle |52is likewise provided with spaced piston portions |52a, |5217, |52c and|52d, as shown. The upper end of each spindle is of reduced diameter toreceive a sleeve |54 which is held in place by means of a thrust washer|55 and a nut |58. Mounted for rotation between the thrust washer and ashoulder on each sleeve |54 is the ilange |60 of a valve-operating nut|62 (see Figs. 4, 6 and 9). The sleeves |46, |48 are held in placeagainst endwise movement within the bores |42, |44 by means of thimbles|64, |66 threaded into the opposite ends of the bores and bearingagainst opposite ends of the sleeves. The thimbles |66, which are on thetop of the block |60, are provided with square threads |68 on which thenuts |62 are mounted. The lead of the threads |66 is. right-handed sothat the valve spindles |50 and |52, which are the shiftable valvemembers, above referred to, will be shifted to the left in Fig. 9, anddown in Fig. 6, when their operating nuts are rotated in a clockwisedirection as viewed in plan in Fig. 9 and in the opposite direction whenthe nuts are rotated in a counterclockwise direction. The clamping rings|32 and |84 are secured to these operating nuts by binding screws |3i,|3|, see Fig. 4, so that movements of the control handle 64, transmitteddin rectly to these clamping rings through links |26, |86, will resultin movements of one or both of the valve spindles, depending on thedirection of movement of the handle from its mid-position with respectto the back end of the gun. That is, if the handle is moved up and donnrelative to the gun, only the valve spindle |56 of the re-s versingvalve 88 will be moved, or if the handle is moved back and f orth fromleft to right rela-l tive to the gun, only the spindle o the reversingvalve |06 will be moved. This is due to the fact that the connectionpoint or" the link |28 to the lever arm H4 is onthe axis line of theblocks H0, ||8 while the link |88 is connected to the arm |24, theposition of which is not changed by up-and-down swinging movements ofthe levers ||4, H6. However, by moving the handle 64 at an angle oneither side of the vvertical and either up or down, both valve spindleswill be shifted from the neutral positions which they occupy in Figs. 6and 9 and, as has already been stated, the motors 60 and 62 each will bestarted into operation.

The valve spindles are held in their neutral positions, and theoperating handle in the midposition shown in Figs. 1 and 4, by means ofopposed spring-pressed plungers bearing against cylindrical portions |33on the ears of the clamping rings |32 and |36. Referring to Figs. 4 and9, plungers |16 and |12 bear against the cylindrical portion |33 on ear|36 of the clamping ring |32 and these plungers are slidably mounted ina bracket member |14 that is mounted on the adaptor rod |13. Eachplunger is provided with a thrust collar |76 adjustably secured theretoby means of a setscrew |16 (Fig. 4). Compression springs |66, |86,surrounding the plungers and interposed between ears |82, |82 on thebracket |16 and the collars |16, thrust the plungers toward each otherto the extent permitted by a second set of ears |84, |84 also carried bythe bracket tilt. Similarly, the plungers |66, |88,

which bear on the cylindrical portion |38 of ear |36 of the otherclamping ring |36, are slidably mounted in two sets of ears |90, |92 ofa bracket |84 that is f secured to the valve block |40 and springs |96,|96 are provided for holding the thrust collars |98, |98 against theinner ears |92, |92 of this bracket. The collars |88, |96 are adjustablysecured to the plungers by setscrews 200 (Fig. 4). The adjustablecollars |16, |716 and |98, |98 are preferably set so that when theoperating handle is released the plungers |10, |12 and |86, |88 justtouch the cylindrical portion |33 of their associated clamping ring earsand the operating nuts |62, |62 are adjusted Within their clamping ringsin such a manner that the valve spindles |50, |52 will be in neutralposition under these conditions.

Pressure fluid is conducted from a suitable source (not shown) to thevalve block by means of a ilexible hose 202 which connects into acentrally located transverse duct 204 (Figs. 6 and 9). Pressure fluid isexhausted by means of a ilexible hose 206 which is connected to avertically extending duct 208 (Fig. '7) that opens into two shorttransverse ducts 2|0, 2|2. Extending at right angles to these transverseducts 204, 2|0, 2|2 arethree lateral ducts 2|4, 2|6 and 2|8 (Fig. 6).Each of the sleeves |46, |48 is provided with ve sets ofcircumferentially arranged apertures 226, 222, 224, 226 and 228 (Fig.8), and the block |66 is cored out to form annular grooves 230, 232,284, 236 and 238 which are vin alinement with the apertures. In theillustrated construction there are eight apertures in each set and insets 222 and 226 four of each eight apertures are of elongated tear-dropshape, while the other four are circular and arranged as shown in Figs.8 and 10. To avoid confusion in Fig. 6, the reference characters forthese apertures and annular grooves are applied, for the most part, onlyto the sleeve |48 and the right-hand side o1' the block associated withthis sleeve but it will be understood that these elements are duplicatedin the sleeve |46 and in the left-hand side of the block. Also, in theschematic view of Fig. 9, some of the elements of the valves have beenomitted in order further to simplify the disclosure. The pipe 64communicates with groove 236 and the pipe 86 with groove 232 associatedwith valve spindle of valve 88, while the hose |04, which is in front ofthe plan of Fig. 6, communicates with the groove 236 and the hose |06with the groove 232 associated with the valve spindle |62 o! valve |08.The pressure fluid supply hose 202 communicates with grooves 234 of bothvalves, through ducts 204 and 2| 6, while the exhaust hose 206communicates with grooves 230 and 238 of both valves, through ductsll,2|2, 2|4 and 2|6.

The operation of each of the two reversing valves is the same and willbe described by reference to valve 88 which controls the operation ofthe motor that swings the gun about a hori- 5 zontal axis. With thevalve spindle |50 in its neutral position, the piston portions |5011,|502) just cover the tear-drop shaped apertures of l the sets 222, 226in the sleeve |46 (see Figs. 6, 9 and 10) and thus cut off flow throughgrooves 232, 286 and the pipes 34, 86. Pressure fluid is, however, beingsupplied toA the space between the e two piston portions from hose 202,ducts ,rd 2|6, and through groove 234 and apertures 24. Now, assumingthat the control handle 64 is moved down, the nut |62 on the spindle |60`by the piston portion |50a on the side toward aperture 220, since thesepiston portions have no lap beyond these tear-drop shaped apertures.Pressure fluid will now iiow through the tear-drop apertures 226 intothe groove 236 l5 and thence, through hose 84, to the-space 90 at theupper end of piston 'I8 and will be exhausted from the space 92 at thebottom of this piston through pipe 86, -groove 232, tear-drop" shapedapertures 222, apertures 220, groove 230, ducts 2M, 2I0 and 208, to hose206. As previously explained, this will cause the motor 60 to swing theback end of the gun down and this movement will, of course, continue solong as the valve spindle is held in this opened lposition. Similarly,upward movement of the operating handle will effect upward movement ofthe back end of the gun. Now the valve spindle moves up (Fig. 6)

or to the right (Figs. 9 and 10), uncovering the large ends of thetear-drop shaped apertures 222 on their sides toward apertures 4224 toadmit pressure uid to groove 232 and to pipe 86 and the small ends ofthe tear-drop apertures 226 on their sides toward apertures 228l thusopening groove 236 and pipe 84 to permit exhaust of fluid 35 throughtear-drop shaped` apertures 226, apertures 226, groove 238, ducts 2|8,2|2 and 208, and hose 206. The action of the other valve spindle |52 tocontrol the operation of the motor 62 is exactly the same as that justdescribed and, as has been already pointed out, movements of the backpart of the gun sidewise are in the same direction as the lateralmovements of the handle 64.

The speed at which the two motors operate will be determined by the rateof flow of pressure uid thereto and exhaust therefrom and the apertures222, 226 are shaped and arranged to provide for regulating this ow. Ashas been stated, the piston portions I a and |50band also piston 50portions |52a and |5212, have no lap and are of such width as just tocover the tear-drop? apertures when in neutral position. Accordingly,the instant that either of these spindles |50, |52 is shifted from itsneutral position, the tear-drop 55 apertures 222 and 226 of itsassociated valve are uncovered and the motor controlled thereby isimmediately started in operation at a speed dep pending on the amountthe apertures are uncovered. Accordingly, if the handle 64 is displaced80 only a little the iiow of pressure iiuid will be small and the actionof the motor, or motors, slow. On the other hand, if the displacement ofthe handle is greater, the ilow of pressure fluid will be larger and thespeed of the motor, or motors, 65 increased. Due, however, to thetear-drop shape of certain of the apertures- 222 and 226 and thearrangement of the circular apertures 222 and 226 with respect to thetear-drop shaped apertures 222 and 226,the increase in the 70 amount ofuncovering of these apertures for admitting pressure uid -occurs at a.greater rate than does the uncovering for exhausting fluid. This will beunderstood by reference to Fig. 10 from which it will be seen that, whenthe spindle 76 50 is moved to the left, the "tear-drop shaped apertures226, through which pressure uid is admitted, are progressively uncoveredat their large ends while the tear-drop shaped apertures 222, throughwhich pressure iuid is exhausted are likewise progressively uncoveredbut at their small ends. Also, the circular apertures 226 are uncoveredbefore the circular apertures 222. The same action takes place in theopposite sense when the spindle is moved to the. right. The shape andarrangement of the apertures 226 and 222 thus provide for a metered owof pressure uid to, and exhaust from, the motors by the progressiveuncovering of these apertures, the rate of which is greater for thoseapertures through which the pressure fluid ows to the motors than forthose through which fluid is exhausted. This shape and arrangementofapertures 222 and 226 insures smoothness of action in the motors bycausing a slight back pressure 'in their exhausting ends.

This back pressure is maintained by the action of apertures 222 and 226until just before the trailing edge of the piston portions a or breaches the middle of the circular apertures 222 or 226, which point issubstantially at 'the extreme normal limit oi move- `ment of the valvespindles |50, |52. In this manner there is always a back pressure, dueto exhaust throttling. in the two motors so that overtravel or runningaway of the motors is prevented and a very smooth action is obtained. Itwill be understood that the number, size and shape of these apertures,as well as the ratio of the number of circular apertures to "teardropshaped apertures, may be varied to suit the different operatingconditions', which may be encountered in this or other types ofapparatus, while still obtaining the metered now and back pressureaction above described. 'I'he valve pistons are all of the same diameterso thatthe spin#- dles are balanced and grooves 240 are provided .in theend pistons c and d to drain back any leakage uid to exhaust.l Sylphonseals 242, 244 are connected to opposite ends of each spindle, as shown.

By mounting the control handle on the device which is to be moved by thetwo' motors,`i. e., on the back end ofthe gun, a virtual follow-upaction is obtained. Referring to Figs. 1, 2 and 9,

and considering first movements of the gun aboutthe horizontal axisprovidedby pins I6, I8, let it be assumed that the operator wishes to'elevate the back end of the gun to aim it along the line X-X (Fig. l) Todo this he grasps the handle 64 and lifts it up. turning the levers ||4and ||6 f through the angle a (Fig. 9). This movement of the handlemoves the shiftable member of the valve 88, through the connections ||4,|20,

|62, |68, immediately .to start the motor 60 in operation to move theback end of the gun up# wards in the same direction as the movement ofthe handle, and this movement of the gun will continue until theshiftable member |50 is returned to. its neutral position. Return of theshiftable member |60 is eected by a. follow-up action from the gun, backthrough the lever H4,

link |28, nut |62 and threads |68 from the handle 64, to the valvespindle |50 when movement of` the handle 64 is stopped. Hence, so longas the operator keeps moving the handle up, the valve spindle |60 willbe displaced and the backend ofthe gun will he moved by the motor 60.

When the desired orientation is reached, in this case when the axis ofthe gun coincides with line XX, the operator holds the handle 'still 1and |96 are required for operating the handle G4. With such l anarrangement, only a slight pressure of the 'l hand is required to movethe handle away from its neutral position and thus start the gun movl1and movement of the gun, by virtue of the followup action justmentioned, returns the spindle |50 to neutral position, whereupon thegun stops. The same kind of action occurs when the handle is moved downfor the purpose of aiming the gun along the line Y-Y. Hence the extentto which the gun is moved is directly and continuously determined by theextent of movement of` the handle 64. Also, the speed at which the gunmoves will be determined by the magnitude of the angle e as this governsthe displacement of the spindle |50 from neutral position. Since, at anyinstant during the movement of the gun the magnitude of the angle a willdepend on the amount the hand is kept ahead of the gun, it follows thatthe speed of movement of the operatcr's hand, directly and continuously,determines the speedof movement of the gun. As has already beenexplained, the direction of movement of the gun is also directly andcontinuously determined by the direction of movement of the handle 64.Swinging movements of the gun about the vertical axis provided by thekingpin 34, by means of the other motor 62, are controlled through thevalve |08 by appropriate movements of' the handle 64 laterally about thepivotal axis of blocks H8, H8 and with the same follow-up action anddirect and continuous control of the speed direction and extent of suchmovement, as will be understood. Combinations of lateral and up-and-downmovements of the handle 64, of course,I will produce correspondingoblique swinging movements of the gun about two axes at right angles toeach other. In fact, the back end of the gun follows all movements ofthe handle 64 in substantially the same manner as if the handle 64 werefixed thereto, the gun being continuously and directly under the controlof the hand which grasps the handle. However, theforces which move thegun are supplied by the pump which delivers pressure fluid to the hose202, and the only muscular effort required of the operator is the smallamount necessary to overcome the resistance of the relatively lightsprings |80, |96. In operating the gun, the gunner experiences the samefeel as though he vwere actually moving the gun in the usual manner, i.e., by gripping the two handles 64 and S6, and he can readily aim thegun, by means of sights 248, 248, on a fixed target or cause it to tracka moving target with the greatest of ease. Furthermore, being relievedof the muscular -eiort which would otherwise be required quickly to movea heavy gun through a large angle or to move the gun against for examplethe slip stream of the propeller of the plane, or to hold it aimedagainst such exterior force, this manipulation of the gun is greatlyfacilitated. inasmuch as the two operating handles 64 and 66 occupy thesame positions on the gun as those usually provided for manualoperation, no new technique need by mastered by the gunner.

VAs has been previously stated, the springs |80 relatively light toreduce the effort If the handle is moved quite far, a very rapidmovement of the gun will follow, and when the gun catches up with thehandle it will be suddenly stopped. There is considerable flexibility inthe gun mount 'and this springiness may cause the gun to bounce somewhatand shake the an exterior force, such as fil ' pressure-operated 12operators hand which is on the handle 64. Such movements of theoperators hand are, of course, transmitted back to the reversing valveswith the result that the movements of the gun become jerky and it wouldbe difficult to aim with any degree of accuracy or to follow a movingtarget in a satisfactory manner. To overcome this tendency, dashpots250, 252 are connected to the lever H6 and arm |24. These-'serve tosteady the movements of the handle 64 and to dampen out any vibrationseither of the gun or of the operators hand.

Having described the invention, what we claim as new and desire tosecure by Letters Patent lof the United States is:

1. In apparatus for training a gun, the combination with a gun mountedfor universal swinging movement about two transverse axes, ofuidmechanisms for swinging the gun, a control means for each of saidmechanisms, an operating member common to all of said control lmeanscomprising a control handle movably mounted on the back end of the gun,in substantially the same location as the usual Ahand grip, to startsaid mechanisms in operation` and means for operating the control meansdirectly by movements of the handle, said control means and saidoperating means being so constructed and arranged that the direction,speed and extent of swinging movement of the gun are directly andcontinuously determined by the direction` speed and extent of movementof the handle.

2. In apparatus for training a gun, the combination with a gun mountedfor universal swinging movement about two transverse axes, olladouble-acting fluid-pressure motor for swinging the gun about each axisrespectively, two reversing valves movable with the gun and adaptedselectively to control the direction and rate of ilowof pressure fluidto and from said different motors respectively, verslng valves, andmeans for actuating said valve-operating means including a controlhandle mounted on the back end of the gun, in substantially the samelocation as the usual hand grip, for movement relative thereto at willby an operator to start said motors in operation and connections betweenthe handle and the gun and between the handle and the operating means,said connections and said valves being so constructed and arranged thatthe direction, speed and extent of the swinging are directly andcontinuously determined by the direction, speed and extent of movementof they,

control handle.

3. In apparatus for training a gun, the combination with a. gun mountedfor universal swinging movement about two transverse axes, of adouble-acting duid-pressure motor for swinging the gun about each axisrespectively, two reversing valves, each of said reversing valves havinga piston for controlling selectively the direction and rate of ow ofpressure iiuid to and from one of the motors, means for normally holdingeach piston in position to cut on ilow to or from a motor, and means fordisplacing each of said pistons in opposite directions from saidposition including a control handle mounted on the back end of the gun,in substantially the same location as the usual hand grip, for movementrelative thereto at will by an operator to start said motors inoperation and connections between the handle and the gun and between thehandle and the displacing means, said conoperating means for saidremovement of the gun i3 nections and said valves being so constructedand arranged that the direction, speed and extent of the swingingmovement of the gun are directly and continuously determined by thedirection, speed and extent of movement of the control handle.

4. In apparatus for training a gun, the combination witha gun mountedfor universal swinging movement' about two transverse axes, of auid-pressure motor including a double-acting piston for swinging the gunabout each axis respectively, a reversing valve associated with eachmotor for controlling the operation vof that motor, each of saidreversing valves comprising a body portion provided with a longitudinalbore and a valve member having spaced piston portions slidable in thebore, a supply conduit leading from a pressure uid source to each ofsaid valves and opening into the bores between said piston portions,connections between the bore of each re-' verslng valve and oppositeends of its associated motor including apertures in the body portionnormally just covered by said piston portions, exhaust conduitsconnected to the bore of each reversing valve, operating means formoving th'e valve members of said reversing valves selectively toconnect their supply conduit to one end of the associated motor throughthe space between the piston portions and simultaneously to connect theopposite end of the motor to one of the exhaust conduits, and a membercommon to both operating means comprising a control handle mounted onthe back end of the gun in substantially the same location as the usualhand grip and movable at will by an operator for operating saidreversing valves, said apertures being so shaped and arranged that thevalve members progressively uncover them as said members are moved,thereby to provide a metered ilow of pressure iluid to, and exhaustfrom, the duid-pressure motors.

5. In apparatus for training a gun, the combination with a gun mountedfor universal swinging movement about two transverse axes, of aduid-pressure motor including a double-acting piston for swinging thegun about each axis respectively, a reversing valve associated with eachmotor for controlling the operation of that motor, each of saidreversing valves comprising a body portion provided with a longitudinalbore and a, valve member having spaced piston portions slidable in thebore, a supply conduit leading from a pressure fluid source to each ofsaid valves and opening into the bores between said piston portions,connections between the bore of each reversing valve and opposite endsof its associated motor including apertures in the body portion normally'just covered by said piston portions, exhaust conduits connected to thebore of each reversing valve, operating means for moving the valvemembers of said reversing valves selectively to connect their supplyconduit to one end of the associated motor through the space -betweenthe piston portions and simultaneously to connect the opposite end ofthe motor to one of the exhaust conduits, and a member common to bothoperating means comprising acontrol handle mounted on the back end ofthe gun in substantially the same location as the usual hand grip andmovable at will by an operator for operating said reversing valves, saidapertures being so arranged and so shaped that the valve membersprogressively uncover them, as thel members are moved, with the rate ofuncovering rate of uncovering of the apertures through 'which pressure.fluid is exhausted from the oppobody portion provided with alongitudinal bore' and a valve member having spaced piston portionsslidable in the bore, a supply conduit leading from a pressure fluidsource to each of said valves and opening into the bores between saidpiston portions, connections between the bore oi each reversing valveand opposite ends of its associated motor including apertures in thebody portion normally covered by said piston portions, exhaust conduitsconnected to the bore of each reversing valve, operating means formoving the valve members of said reversing valves selectively to connecttheir supply conduit to one end of the `associated motor through thespace between the piston portions and simultaneously to connect theopposite end of the motor to one of the exhaust conduits, and a membercommon to both operating means comprising o, control handle mounted onthe back end of the gun in substantially the same location as the usualhand grip and movable at will by an operator for operating saidreversing valves, said piston portions being of such size as exactly tocover said apertures so that the motors' are operated immediately uponthe slightest movement of the valve members in either direction from aneutral position and are blocked against movement by exterior forcesacting on the gun when said valve members are returned to said neutralposition.

7. In apparatus for training a gun, the combination with a gun mountedfor universal swinging movement about two transverse axes, of adouble-acting fluid-pressure motor for swinging the gun about each axisrespectively, two reversing valves, each of said reversing valves havinga casing and a piston for controlling selectively the direction and rateof ow oi pressure uid to and from one of the motors, means for normallyholding the pistons in position to cut ofi flow to or from the motors,means for displacing each of said pistons in opposite directions fromsaid position, a control handle mounted on the back end of the gun, insubstantially the same location as the usual hand grip, for movementrelative thereto by an operator, connections between the'handle and thegun and between the handle and the displacing means .so Aconstructed andarranged that the direction, speed and extent of the swinging movementsof the gun by said-motors are directly and continuously determined bythe direction, speed and extent of movement of the cont-rol handle bythe operator, each of said plston-displacing means comprising a nutthreaded to the casing and operatively connected to the correspondingpiston and said connections between the handle and piston-displacingmeans including linkages for eiecting rotation of the nuts anddisplacement of the pistons by movement of the handle.

`8. In apparatus for training a gun, the combination with a gun mountedfor universal swinging movement about two transverse axes, ofuidpressure motors for swinging the gun respectively about said axes,valve means for directly controlling the direction and rate of flow ofpressure fluid to and from the motors, a control handie mounted on theback end oi the gun, ln substantially the same location as the usualhand grip, and movable relatively thereto at will by an operator foroperating said valves selectively to effect swinging movement of 'thegun by the motors, operative connections between'said handle and thevalve means so constructed and arranged l that thedirection, speed andextent of swinging movementv of the gun by the duid-pressure motors aredirectly and continuously determined by the direction, speed and extentof movement of the handle by the operator, and dash pots associated withsaid handle for steadylng its movey ments relative to the gun.

9. In apparatus for training a gun, the combination with a gun mountedfor universal movement about two transverse axes, of a, double-actingfluid-pressure motor for swinging the gun about each axis respectively,two reversing valves, each of said valves having a casing and a pistonof iiow of pressure fluid to and from one of the motors, means fornormally holding the pistons in position to cut of! ilow to or from themotors, means for displacing each of said pistons in opposite directionsfrom said position, a control handle mounted on the back end of the gun,in substantially the same location as.the usual hand grip, for movementrelative thereto by an, operator, connections between the handle and thegun and between the handle and the displacing means so constructed andarranged that the direction, speed and extent of the swinging movementsof the gun by said motors are directly and continuously determined bythe direction, speed and extent of movement of the control handle by theoperator, each of said piston-displacing means comprising a rotatablemember and Said connections including linkages for effecting rotationoi.' said members by movement of the handle.

FRED V. HART. JOHN F. D. SMITH. LAll/CBERT S. LINDEROTH, JR.

